The invention relates to a filtering element for filtering devices comprising a filtering material which defines a filtering space, intended for the filtration of fluids, such as hydraulic fluids, and at least one water indicator which is provided at a location coming into contact with a fluid during filtration mode and indicates the presence of water in the fluid in a visually recognizable manner.
For the operational safety of hydraulic systems and other technical installations that work with fluid operating materials, operational safety largely depends on the associated filtering devices working trouble-free. A requisite for this is for the filtering elements of the filtering devices to remain fully and perfectly functional over the entire time of use between the specified filter changes. In view of the high material value of the relevant hydraulic systems and the cost associated with failure, one is forced to pay particular attention to maintaining the specified operating conditions to prevent potential malfunctions. When filtering elements are removed at the exchange intervals, the filtering elements are therefore carefully checked for potential damage which arose during operation. However, it has been shown in practice that, when damage or impairments are identifiable with, for example, the filtering medium of the removed filtering element, it is difficult or even impossible to deduce the precise cause of the impairment or damage.
A filtering element of the initially cited type is known from DE 69 19 836 U. An oil furnace tank filter is known that consists of a cylindrical body open on top with a molded-on base in whose top open part a filling funnel is arranged with at least one contaminant separating filter arranged therein, and a mechanical sludge and water trap is provided in its base. A water indicator is arranged at the top contaminant separating filter and on the base of the cylindrical body. The water indicator can consist of a water-indicating reaction paper, a water-indicating granulate, or a paste. The water-indicating indicators make it possible to remove water that is present in a timely manner from the device.
Today's highly effective filtering media react problematically to the presence of water in fluid so that the filtering effect can suffer from operation with fluids that are contaminated with a proportion of water. If the filtration quality decreases while operating a hydraulic system without exceeding the permissible operating limits such as the pressure level, maximum volumetric flow, differential pressure (bypass valve response) or the like, it can be determined whether the problem was caused by water in the fluid while changing the filtering element. The system operator is therefore able to undertake the appropriate, corresponding countermeasures and thereby cause the trouble-free filtration mode.
In view of these problems, the object of the invention is to provide a filtering element whose use promotes the safe operation of the filtering device and hence the associated system and makes it possible to easily manufacture the filtering element.